Noise from audio amp board

Other Hardware General Electronics
1

For a installation I'm working on I'm using 8 of those audio amplifier boards.
Each two boards are powered by a 12V 2A power supply using a splitter

each board get is output from a 8 channel outputs audio interface.
Each board is connected to an either 8ohm or 4ohm speaker that I took apart from a found speakers.

The issue I'm having is a lot of noise that get amplified when I'm turning the board potentiometer. Some board has much more noise than other and some very little of noise.

Does someone have an idea what it could be ?

2

Electrically noisy power supply, long, unshielded input leads acting as antennas, defective modules, etc.

3

Some volume control pots get noisy when they are used a lot or because their circuits pass DC current through them. The differences in noise level you hear may be due to the different characteristics of the speakers in use.

4

When you decided to go with these boards have you read any reviews seen any examples of successful implementation?

5

Those are inductor-less (= cheaper) class-D amplifiers.
Is the noise also there with no input wires connected and the pot turned down.
The speaker leads most be short and twisted, because they carry a several hundred kHz square wave that can get transmitted to other circuits.
Leo..

6

The power supply is sufficient for only one board (20 W total, maximum output into 8 Ohm speakers).

In any case, get just one amplifier working to your satisfaction, before attempting to add more.

7

What is the calculation you have made?

8

I added 10W and 10W to get 20W. Took some head-scratching, for sure!

HiLetgo PAM8610 Mini Stereo AMP Audio Amplify Board Digital Portable Ampli Module 10W+10W Dual Channel Amplifier Class-D 12V DC

9

those it mean 10W per speaker? so if I'm using only 1 speaker its 10W and not 20W?

What I mean to ask is how did you calculate the the board need 2A of current?

the calculation is power divided by voltage equal current?

So if the board power is 20W and the power supply is 12V the current is 20W/12V = 1.66A
?

10

Each module has two independent amplifiers. You need only four modules for eight speakers.

12V x 2A = 24 Watts, which will power only one module with two speakers at full volume (20 W total).

Power supplies should always be chosen to have excess capacity. It is bad idea to operate any electronic circuit at its limits.

11

Hi,

Please clarify?
If you leave the pot in any position, do you get noise?
Does the noise appear/increase if you just touch the pot shaft?
If the noise is there ONLY when you turn the pot, then you have a noisy pot.
If the noise is there even when you don't turn the pot, then you are probably picking up noise from an external source.
Do you have any microcontrollers working in your project?

Can you please post an image(s) of your project?

Thanks... Tom... :smiley: :+1: :coffee: :australia:

12

when pot is fully counterclockwise there is no noise. As I'm turning the pot clockwise the noise is increasing and it there also when I'm not in the act of turning the pot.

From what I can remember the answer is no , or at least not so noticeable.

Yes, I guess that is the case.

I do have an arduino and some mosfets controlling small solenoids. The arduino/solenoids/mosfets are around 3 meter apart from the amplifier boards.

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The longest wire between speaker to board is no more than 4 meter I guess .

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13

I'm using only 1 speaker per board as the signal I am using is mono

so if I'm using only 1 speaker per board we could say that either a 12V 1A power supply is enough or 12V 2A power supply could potentially deliver power for 2 boards?

What does it matter / Is it matter if I'm using 8ohm or 4ohm speaker?

14

The 4 ohm speaker might take 3 amps on its own...
So you may damage your board if the board is not somehow internally protected.

15

What is the calculation for how much current a 4ohm speaker will take?

12V/4R ? = 3A ?

16

Google ohms law...

17

I guess my calculation is right but I get confused when I need to consider the amplifier board specification.
It say it can deliver up to 10W per speaker.

so if I'm using 1 8ohm speaker with 12V power supply we can say that it needed 1.5A of current?

then If I know that the board can deliver 10W of power with 12V power supply it leaves as with 0.8333A ?

18

Hi,

As you say you have no noise when the pot is turned right down, the noise is from the wires that provide the signal to the amps.
Are you using audio shielded cable, like most audio installations do?

Where in your picture are the amplifiers and their pots?

What noise do you get if you disconnect power from the UNO?

Thanks.. Tom.... :smiley: :+1: :coffee: :australia:

19

From Audio interface to the amplifier board line input I'm using trs cable and from amplifier board to speaker I'm using that RCA cable

I marked it in yellow

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I'm afraid I will be able to check it only tomorrow but now when you say that I remembered that when using the amplifier boards without the uno and the mosfets/solenoid boards there was less noise from the amplifiers and speakers.
If the Uno is the reason - anything I can do about? assuming the setup can't be changed location wise.

20

You have a class D amplifier.
It will (very fast) turn on and off the power to your speaker. At most it will be 50% on. Then it will take 1.5 amps at 8 ohm (neglecting that impedance will be higher than 8 ohms...). So .75A on average times 12 V is 9 W...
The specs of these boards tend to be very optimistic...
Also, the specs of the board should state the min and max speaker resistance. So look that up...